Estimate of uplink capacity in overlaid macrocell/multi-microcell CDMA WLL systems

The authors have produced overlaid macrocell multi-microcell CDMA wireless local loop (WLL) systems and presented the parameters for the coexistence of the overlaid macrocell/multi-microcell, and then calculated the uplink capacity of the microcell in the proposed system. Also, the frequency division CDMA (FD-CDMA) system has been applied to reduce the inter-system interference. From the results, we have known that the capacity of the microcell has diminished with the increase of the number of users, the signal to interference power ratio in the neighboring system, and the ratio of micro and macro cell radius. However, as the distance between the base stations of the microcells is increased, the microcell capacity increases. When it is assumed that the interference signals are dispersed equally at each subband, the applied FD-CDMA technique which has been designed to have capacity flexibility with respect to the traffic variation has improved the capacity up to 50% even if the processing gain of each subband is smaller than that of the W-CDMA system.